Thin film magnetic head

ABSTRACT

A thin film magnetic head includes a lower shielding layer composed of a magnetic material; a nonmagnetic MR gap layer on the lower shielding layer; a magnetoresistive element layer in the MR gap layer facing a recording medium; a lower core layer composed of a magnetic material on the MR gap layer; an upper core layer composed of a magnetic material being opposed to the lower core layer with a nonmagnetic gap layer therebetween at the surface facing the recording medium; and a coil layer for inducing a recording magnetic field in the lower core layer and the upper core layer. Alternatively, a thin film magnetic head further includes a first magnetic material layer in the rear of the lower shielding layer, magnetically separated from the lower shielding layer. A method of fabricating the same is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin film magnetic head in which arecording head (inductive magnetic head) and a reproducing head(magnetoresistive head) are combined, and more particularly, to a thinfilm magnetic head in which the tip and the vicinity thereof of an uppercore layer can be formed in a predetermined shape, enabling the track tobe narrowed, and to a method of fabricating the same.

2. Description of the Related Art

FIG. 11 is a longitudinal sectional view of a conventional thin filmmagnetic head.

The thin film magnetic head is provided on the trailing end of a sliderof a floating type magnetic head which faces a recording medium such asa hard disk, and is a combined thin film magnetic head in which amagnetoresistive head for reproducing, using magnetoresistance, and aninductive magnetic head for recording, are laminated.

A lower shielding layer 1 is composed of a magnetic material such as anNiFe alloy (permalloy), and a magnetoresistive element layer 2 is formedon the lower shielding layer 1 with a first gap layer (not shown in thedrawing) therebetween. An upper shielding layer 3, which is composed ofa magnetic material such as an NiFe alloy, is formed on themagnetoresistive element layer 2. As described above, the thin filmmagnetic head shown in FIG. 11 is a combined thin film magnetic head inwhich a magnetoresistive head and an inductive magnetic head arelaminated, and the upper shielding layer 3 also functions as a lowercore layer of the inductive magnetic head. Hereinafter, the layerrepresented by numeral 3 is referred to as a lower core layer.

A gap layer 4 (second gap layer) composed of a nonmagnetic material suchas aluminum oxide (Al₂O₃) or silicon dioxide (SiO₂) is formed on thelower core layer 3. An insulating layer 5 (first insulating layer)composed of a resist or other organic material is formed on the gaplayer 4.

A coil layer 6, composed of a conductive material having low electricalresistance, such as Cu, is spirally formed on the insulating layer 5.Although the coil layer 6 is formed so as to go around a base 8 b of anupper core layer 8, which will be described later, only a portion of thecoil layer 6 is shown in FIG. 11.

The coil layer 6 is covered by an insulating layer 7 (second insulatinglayer) composed of an organic material or the like, and the upper corelayer 8 is formed on the insulating layer 7 by plating a magneticmaterial such as a permalloy. The tip 8 a of the upper core layer 8 isjoined to the lower core layer 3 with the gap layer 4 therebetween atthe section facing a recording medium to form a magnetic gap having agap length Gl. The base 8 b of the upper core layer 8 is magneticallyconnected to the lower core layer 3 through a hole made in the gap layer4.

In the inductive magnetic head for writing, when a recording current isapplied to the coil layer 6, a recording magnetic field is induced inthe lower core layer 3 and the upper core layer 8, and a magnetic signalis recorded onto a recording medium such as a hard disk by means of aleakage magnetic field from the magnetic gap between the lower corelayer 3 and the tip 8 a of the upper core layer 8.

In the thin film magnetic head shown in FIG. 11, the coil layer 6 has adouble-layered structure. The double-layered structure is employed forthe purposes of enhancing writing efficiency by shortening the magneticpath formed over the lower core layer 3 and the upper core layer 8, andreducing inductance.

FIG. 12 is a longitudinal sectional view which shows a step offabricating the upper core layer 8 of the thin film magnetic head shownin FIG. 11.

The upper core layer 8 of the thin film magnetic head shown in FIG. 11is formed by frame plating. As shown in FIG. 12, after the coil layer 6is formed and is covered by the insulating layer 7, an underlying layer9 composed of a magnetic material such as an NiFe alloy is formed fromon the gap layer 4, which is exposed around the tip, to on theinsulating layer 7.

Next, after a resist layer 10 is formed on the underlying layer 9, apattern of the upper core layer 8 is formed on the resist layer 10 byexposure and development, and a magnetic material layer (upper corelayer 8) is formed by plating on the section in which the resist 10 isremoved and the underlying layer 9 is exposed. When the remaining resistlayer 10 is removed, the upper core layer 8 is completed. In the finalstep, by removing the thin film laminate on the left side of the lineA—A (shown by dotted lines in the drawing), the thin film magnetic headhaving the shape shown in FIG. 11 can be obtained.

However, in the structure of the conventional thin film magnetic head asshown in FIG. 11, when the upper core layer 8 is formed by frameplating, narrowing of the track cannot be realized.

As shown in FIG. 11, by forming the coil layer 6 having a double-layeredstructure, the total thickness of the insulating layers 5 and 7 whichcover the coil layer 6 is increased, and in such a state, as shown inFIG. 12, when the resist layer 10 is formed from on the gap layer 4around the tip in which the insulating layers 5 and 7 are not formed toon the insulating layer 7, the thickness t1 of the resist layer 10formed on the gap layer 4 is significantly increased. On the gap layer4, as shown in FIG. 11, the tip 8 a of the upper core layer 8 is formed.The tip 8 a is narrowly shaped as shown in the plan view of FIG. 13, andthe width of the tip 8 a determines a track width Tw. In particular, asrecording density is increased, the track width Tw must be furtherdecreased, and the pattern of the resist layer 10 must be formed withparticular precision when the tip 8 a and its vicinity of the upper corelayer 8 are formed.

However, as shown in FIG. 12, since the thickness t1 of the resist layer10 on the gap layer 4, in which the tip 8 a of the upper core layer 8 isto be formed, is significantly increased, when the wavelength of a lightsource for exposure is decreased and the depth of focus is increased,resolution (resolving power) is degraded and the track width Tw having apredetermined size cannot be obtained; it is thus not possible to meetthe need for narrowing of a gap. In order to improve resolution, asmaller depth of focus is better.

Another reason for not being able to realize narrowing of the track isthat since the thickness t1 of the resist layer 10 formed on the gaplayer 4 differs greatly from that of the resist layer 10 formed on theinsulating layer 7, irregular reflection may occur during exposure anddevelopment because of differences in focus.

FIG. 14 is a longitudinal sectional view of another conventional thinfilm magnetic head.

In FIG. 14, a lower shielding layer 11 is partially formed only aroundthe tip, and a magnetoresistive element layer 12 is formed on the lowershielding layer 11. A lower core layer 13 (upper shielding layer) isformed from on the magnetoresistive element layer 12 and to in the rearof the lower shielding layer 11. A coil layer 14 is formed on the lowercore layer 13, and an upper core layer 15 is formed so as to face thelower core layer 13 at the tip and to extend over an insulating layer 17formed on the coil layer 14.

In the conventional example, the lower shielding layer 11 is partiallyformed only around the tip, and in the rear of the lower shielding layer11, the lower core layer 13 is lowered to the same level as that of thelower shielding layer 11 through an inclined plane 13 a. As shown inFIG. 14, the coil layer 14 is formed from on the inclined plane 13 a toon the lower core layer 13 lying in the rear of the inclined plane 13 a.Therefore, the insulating layer 17 is formed on the coil layer 14, beingswollen from the surface S of the lower core layer 13 in the tip sectionby height t5, and the height t5 is smaller than the total thickness ofthe insulating layers 5 and 7 of the thin film magnetic head shown inFIG. 11. Accordingly, the thickness of a resist layer (not shown in thedrawing; refer to numeral 10 in FIG. 12), which is formed on the lowercore layer 13 around the tip, is not extremely increased, and incomparison with the thin film magnetic head shown in FIG. 11, a tip 15 aof the upper core layer 15 can be easily formed in a predeterminedshape.

In the thin film magnetic head shown in FIG. 14, however, the followingproblems may occur.

Generally, when a thin film magnetic head is formed, a plurality of thinfilm magnetic heads is simultaneously formed on a substrate 16 and bydividing into the individual thin film magnetic heads in the end, thethin film magnetic head shown in FIG. 14 can be obtained. That is,first, a plurality of lower shielding layers 11 is formed on thesubstrate 16, and a magnetoresistive element layer 12 is formed on eachlower shielding layer 11 with an insulating layer (not shown in thedrawing) therebetween. Next, a resist layer is applied onto a pluralityof magnetoresistive element layers 12, and a track width Tw of themagnetoresistive element layer 12 is determined by exposure anddevelopment.

However, as described above, a plurality of magnetoresistive elementlayers 12 is placed on the substrate 16, and when the resist layer is,for example, spin-coated thereon, the surface onto which the resistlayer is applied is not planar because the lower shielding layers 11 areselectively formed and there are steps between the lower shieldinglayers 11 and the substrate 16. Therefore, the resist layer is notformed at a uniform thickness, and a plurality of magnetoresistiveelement layers 12 formed on the substrate 16 cannot have a predeterminedtrack width Tw.

In the thin film magnetic head shown in FIG. 14, the lower core layer 13is provided with the inclined plane 13 a, and the coil layer 14 isformed from on the inclined plane 13 a to on the rear of the lower corelayer 13. Since there is a difference in level on the inclined plane 13a on which the coil layer 14 is to be formed, the coil layer 14 isformed on the inclined plane 13 a at a position that is raised upward inthe drawing, and thus the thickness of the insulating layer 17 forcovering the coil layer 14 must be increased. If the thickness of theinsulating layer 17 is increased, it is difficult to form the tip 15 aof the upper core layer 15 at a predetermined shape by frame plating,and narrowing of the track cannot be realized.

SUMMARY OF THE INVENTION

The present invention overcomes the difficulties noted above withrespect to the related art. It is an object of the present invention toprovide a thin film magnetic head, in which narrowing of the track isenabled by reducing the swelling of an insulating layer formed on a coillayer so that a tip of an upper core layer is formed in a predeterminedshape and a magnetoresistive element layer is formed at a predeterminedtrack width Tw, and to provide a method of fabricating the same.

In one aspect, a thin film magnetic head, in accordance with the presentinvention, includes a lower shielding layer composed of a magneticmaterial; a nonmagnetic MR gap layer formed on the lower shieldinglayer; a magnetoresistive element layer lying in the MR gap layer andfacing a recording medium; a lower core layer composed of a magneticmaterial formed on the MR gap layer; an upper core layer composed of amagnetic material being opposed to the lower core layer with anonmagnetic gap layer therebetween at the surface facing the recordingmedium; and a coil layer for inducing a recording magnetic field to thelower core layer and the upper core layer. The lower core layer extendsfrom the position facing the recording medium to the rear of themagnetoresistive element layer, bends toward the lower shielding layerin the rear, and comes into magnetic contact with the lower shieldinglayer. The coil layer lies in the rear of a step of the back end of thelower core layer and lies magnetically between the lower shielding layerand the core layer. A magnetic path induced by the coil layer is formedover the lower shielding layer, the lower core layer, and the upper corelayer.

In another aspect, a thin film magnetic head, in accordance with thepresent invention, includes a lower shielding layer composed of amagnetic material; a first magnetic material layer formed in the rear ofthe lower shielding layer and being magnetically separated from thelower shielding layer; a nonmagnetic MR gap layer formed on the lowershielding layer; a magnetoresistive element layer lying in the MR gaplayer and facing a recording medium; a lower core layer composed of amagnetic material formed on the MR gap layer; an upper core layercomposed of a magnetic material being opposed to the lower core layerwith a nonmagnetic gap layer therebetween at the surface facing therecording medium; and a coil layer for inducing a recording magneticfield to the lower core layer and the upper core layer. The lower corelayer extends from the position facing the recording medium to the rearof the magnetoresistive element layer, bends toward the first magneticmaterial layer in the rear, and comes into magnetic contact with thefirst magnetic material layer. The coil layer lies in the rear of a stepof the back end of the lower core layer and lies magnetically betweenthe first magnetic material layer and the upper core layer. A magneticpath induced by the coil layer is formed over the first magneticmaterial layer, the lower core layer, and the upper core layer.

In the above thin film magnetic head, preferably, a nonmagnetic materiallayer is provided between the lower shielding layer and the firstmagnetic material layer, and the lower shielding layer, the firstmagnetic material layer, and the nonmagnetic material layer have thesame thickness.

In the present invention, preferably, the lower shielding layer and thefirst magnetic material layer are composed of different magneticmaterials, and for example, the first magnetic material layer iscomposed of a magnetic material having higher saturation flux densityand/or higher resistivity than that of the lower shielding layer.

A second magnetic material layer may be formed on the lower shieldinglayer or the first magnetic material layer in the rear of the coillayer, and the upper core layer is brought into contact with the secondmagnetic material layer.

Preferably, the second magnetic material layer is composed of a magneticmaterial having higher saturation flux density and/or higher resistivitythan that of the lower shielding layer.

In the present invention, the coil layer may be formed in adouble-layered structure, and at least the lower coil layer is placed inthe rear of a step of the back end of the lower core layer, thusenabling a larger recording magnetic field and a thinner head.

In still another aspect, a method of fabricating a thin film magnetichead, in accordance with the present invention, includes the steps of:forming a lower shielding layer composed of a magnetic material by frameplating; forming a first gap layer on the lower shielding layer andforming a magnetoresistive element layer thereon for facing a recordingmedium; making a hole in the first gap layer in the rear of themagnetoresistive element layer so as to reach the lower shielding layerand forming a lower core layer extending from the hole to on themagnetoresistive element layer by frame plating; forming a second gaplayer composed of a nonmagnetic material from on the lower core layer toon the first gap layer formed in the rear of the lower care layer;forming a first insulating layer on the first gap layer in the rear ofthe lower core layer with the second gap layer therebetween and forminga coil layer on the first insulating layer; and forming a secondinsulating layer on the coil layer, and then forming an upper core layerfrom on the gap layer formed on the lower core layer to on the secondinsulating layer by frame plating.

Alternatively, a method of fabricating a thin film magnetic head, inaccordance with the present invention, includes the steps of: forming alower shielding layer composed of a magnetic material and a firstmagnetic material layer lying in the rear of the lower shielding layerby frame plating; forming a first gap layer on the lower shielding layerand the first magnetic material layer, and forming a magnetoresistiveelement layer thereon for facing a recording medium; making a hole inthe first gap layer in the rear of the magnetoresistive element layer soas to reach the first magnetic material layer and forming a lower corelayer extending from the hole to on the magnetoresistive element layerby frame plating; forming a second gap layer composed of a nonmagneticmaterial from on the lower core layer to on the first gap layer formedin the rear of the lower care layer; forming a first insulating layer onthe first gap layer in the rear of the lower core layer with the secondgap layer therebetween and forming a coil layer on the first insulatinglayer; and forming a second insulating layer on the coil layer, and thenforming an upper core layer from on the gap layer formed on the lowercore layer to on the second insulating layer by frame plating.

The method may include the steps of forming a nonmagnetic material layerbetween the lower shielding layer composed of a magnetic material andthe first magnetic material layer in the rear of the lower shieldinglayer, and grinding the lower shielding layer, the first magneticmaterial layer, and the nonmagnetic material layer down to the samethickness.

Before the second gap layer is formed, a hole may be made in the firstgap layer on the lower shielding layer or the first magnetic materiallayer in the rear of the section in which the coil layer is formed, asecond magnetic material layer may be formed by frame plating, and theupper core layer may be formed so as to be brought into contact with thesecond magnetic material layer through the hole.

Furthermore, the coil layer may be formed in a doublelayered structure,and at least the lower coil layer may be formed in the rear of the lowercore layer.

Preferably, the first magnetic material layer and the second magneticmaterial layer are composed of a magnetic material having highersaturation flux density and/or higher resistivity than that of the lowershielding layer.

In the present invention, a lower core layer (upper shielding layer) ispartially formed only around the tip of a thin film magnetic head, thelower core layer bends perpendicularly on the back of a magnetoresistiveelement layer to form a step, and the lower core layer is brought intocontact with a lower shielding layer or a first magnetic material layer.A coil layer is formed in the rear of the lower core layer that is bentperpendicularly, and thus the swelling of an insulating layer forcovering the coil layer can be decreased in relation to the surface ofthe lower core layer exposed around the tip. Therefore, in the presentinvention, a resist layer used when an upper core layer is formed can beformed thinly without a large difference in the film thickness from onthe lower core layer exposed around the tip to on the insulating layercovering the coil layer. The tip of the upper core layer formed on thelower core layer exposed around the tip is an important section fordetermining a track width Tw, and in the present invention, the tip ofthe upper core layer can be properly formed in a predetermined shape,thus meeting the demand to narrow the track.

Next, differences between the structure of a thin film magnetic head inthe present invention and that of the conventional thin film magnetichead shown in FIG. 14 will be described.

In the present invention, in the manner same as that in the thin filmmagnetic head shown in FIG. 14, a lower shielding layer may be formedonly around the tip, and as a specific structure, a thin film magnetichead shown in FIG. 2 may be presented.

A difference between the present invention and the conventional thinfilm magnetic head shown in FIG. 14 is that in the present invention, asshown in FIG. 2, in the rear of a lower shielding layer 30, a firstmagnetic material layer 31 having the same height as that of the lowershielding layer 30 is formed with a predetermined distance L2therebetween, and in contrast, in the conventional thin film magnetichead shown in FIG. 14, in the rear of the lower shielding layer 11, thelower core layer 13 is formed by lowering its position through theinclined plane 13 a.

In the present invention, after the lower shielding layer 30 and thefirst magnetic material layer 31 are formed, a nonmagnetic materiallayer 32 composed of Al₂O₃ or the like is formed between the lowershielding layer 30 and the first magnetic material layer 31, andsurfaces of the lower shielding layer 30, the first magnetic materiallayer 32, and the nonmagnetic material layer 32 are planarized. Amagnetoresistive element layer 22 formed on the lower shielding layer 30is formed into a predetermined shape by a resist layer (not shown in thedrawing). Since the resist layer is applied onto the planarized lowershielding layer 30, first magnetic material layer 31, and nonmagneticmaterial layer 32, the resist layer can be formed at a uniformthickness, and therefore, the magnetoresistive element layer 22 can beformed at a predetermined track width Tw by the resist layer.

In contrast, in the conventional thin film magnetic head shown in FIG.14, only the lower shielding layer 11 is partially formed on thesubstrate, and when a resist layer (not shown in the drawing) forforming the magnetoresistive element layer 12 into a predetermined shapeis applied onto the lower shielding layer 11, because of a difference inlevel between the substrate 16 and the lower shielding layer 11, theresist layer cannot be formed at a uniform thickness, resulting instrain in the magnetoresistive element layer 12, and thus the trackwidth Tw of the magnetoresistive element layer 12, which must be formedwith particular precision, cannot be formed properly.

In the thin film magnetic head shown in FIG. 14, since the inclinedplane 13 a is provided in the lower core layer 13, a difference in leveleasily occurs in the section in which the coil layer 14 is formed in therear of the lower core layer 13. In the present invention, as shown inFIG. 2, since the lower core layer 33 is formed perpendicularly from thefirst magnetic material layer 31, a coil layer 27 formed in the rear ofthe lower core layer 33 can be formed on a planarized first gap layer 23with a second gap layer 25 and an insulating layer 26 therebetween, andthus, the formation of the coil layer 27 is facilitated and the swellingof an insulating layer 28 formed on the coil layer 27 can be reduced asmuch as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a thin film magnetic head asa first embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of a thin film magnetic head asa second embodiment of the present invention;

FIG. 3 is a longitudinal sectional view of a thin film magnetic head asa third embodiment of the present invention;

FIG. 4 is a longitudinal sectional view which shows a step offabricating a lower shielding layer and a first magnetic material layerof a thin film magnetic head in the present invention;

FIG. 5 is a longitudinal sectional view which shows a fabricating stepperformed subsequent to the step shown in FIG. 4;

FIG. 6 is a longitudinal sectional view which shows a fabricating stepperformed subsequent to the step shown in FIG. 5;

FIG. 7 is a longitudinal sectional view which shows a fabricating stepperformed subsequent to the step shown in FIG. 6;

FIG. 8 is a longitudinal sectional view which shows a step offabricating an upper core layer of a thin film magnetic head in thepresent invention;

FIG. 9 is a plan view which shows a fabricating step performedsubsequent to the step shown in FIG. 8;

FIG. 10 is a longitudinal sectional view which shows a fabricating stepperformed subsequent to the step shown in FIG. 9;

FIG. 11 is a longitudinal sectional view of a conventional thin filmmagnetic head;

FIG. 12 is a longitudinal sectional view which shows a step offabricating an upper core layer of the thin film magnetic head shown inFIG. 11;

FIG. 13 is a plan view of an upper core layer; and

FIG. 14 is a longitudinal sectional view of another conventional thinfilm magnetic head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 a longitudinal sectional view of a thin film magnetic head as afirst embodiment of the present invention.

A thin film magnetic head shown in FIG. 1 is a so-called “combined thinfilm magnetic head” in which a reproducing head (magnetoresistive head)using magnetoresistance and an inductive magnetic head for recording arelaminated. The left end in the drawing shows a surface being opposed toa recording medium, i.e., air bearing surface (ABS).

A lower shielding layer 21 composed of a magnetic material such as anNiFe alloy is formed on a substrate 20. An MR gap layer 23 (first gaplayer) is formed on the lower shielding layer 21, and a magnetoresistiveelement layer 22 is formed being interposed between the gap layers 23 onthe tip side of the lower shielding layer 21 (on the side facing therecording medium; on the ABS side). As the magnetoresistive elementlayer 22, for example, a giant magnetoresistive (GMR) elementrepresented by a spin-valve element or an anisotropic magnetoresistive(AMR) element may be selected. As shown in FIG. 1, the thickness of thegap layer 23 corresponds to a gap length Gll.

In the present invention, as shown in FIG. 1, a hole 23 a, which passesthrough the gap layer 23 and reaches the lower shielding layer 21, ismade in the rear of the magnetoresistive element layer 22 (on the rightside in the drawing). A lower core layer 24 is formed to extend from thehole 23 a to on the magnetoresistive element layer 22. The lower corelayer 24 also functions as an upper shielding layer of the reproducinghead. The lower core layer 24 is composed of a magnetic material such asan NiFe alloy.

As shown in FIG. 1, the lower core layer 24 extends perpendicularly fromthe surface of the lower shielding layer 24 and bends over themagnetoresistive element layer 22. A gap layer 25 (second gap layer)composed of an insulating material is formed from on the lower corelayer 24 to on the first gap layer 23. As shown in FIG. 1, the secondgap layer 25 formed on the first gap layer 23 is lowered by aright-angled step in comparison with the second gap layer 25 formed onthe lower core layer 24, and an insulating layer 26 (first insulatinglayer) composed of a resist material or other organic material is formedon the second gap layer 25 formed at the lower level. A coil layer 27composed of a conductive material such as Cu having low electricalresistance is spirally formed on the insulating layer 26. An insulatinglayer 28 (second insulating layer) composed of an organic material isformed on the coil layer 27.

In the present invention, as shown in FIG. 1, the coil layer 27 isformed in the rear of the lower core layer 24, and in particular, sincethe lower core layer 24 formed on the magnetoresistive element layer 22is bent perpendicularly toward the lower shielding layer 21, a step isformed between the lower core layer 24 and the first gap layer 23. Thecoil layer 27 is formed at the lower level. Therefore, the secondinsulating layer 28 on the coil layer 27 is formed being slightlyswelled by t2 from the surface S of the second gap layer 25 formed onthe lower core layer 24, or is formed substantially at the same heightas the surface S of the gap layer 25. Thus, the swelling of the secondinsulating layer 28 can be reduced in comparison with the conventionalthin film magnetic head.

An upper core layer 29 composed of a magnetic material is formed from onthe second gap layer 25 to on the second insulating layer 28. As shownin FIG. 1, a tip 29 a of the upper core layer 29 is formed on the lowercore layer 24 with the second gap layer 25 therebetween at the sectionfacing a recording medium, and a magnetic gap having a gap length G12 isformed. A base 29 b of the upper core layer 29 is magnetically connectedto the lower shielding layer 21 through a hole made in the gap layers 23and 25 and insulating layers 26 and 28.

The upper core layer 29 is formed by frame plating as described below.In the frame plating process, a resist layer is formed from on thesecond gap layer 25 formed on the lower core layer 24 to on the secondinsulating layer 28, and after the resist layer is exposed anddeveloped, the upper core layer 29 is formed by plating.

In the present invention, as described above, the second insulatinglayer 28 on the coil layer 27 is formed being slightly swelled by t2from the surface S of the second gap layer 25 formed on the lower corelayer 24, and thus the resist layer to be formed from on the second gaplayer 25 formed on the lower core layer 24 to on the second insulatinglayer 28 can be formed thinly at a substantially uniform thickness.Therefore, in the present invention, the depth of focus during exposureand development can be decreased and resolution can be improved.Irregular reflection due to differences in focus does not easily occur,and in particular, the narrowly shaped tip 29 a of the upper core layer29, in which the width thereof determines a track width Tw, can beformed properly in a predetermined shape, and thus narrowing of thetrack is enabled.

Next, material properties will be described. The lower shielding layer21 which functions as a shield is preferably composed of a magneticmaterial having high permeability, such as an NiFe alloy. The lower corelayer 24 functions as a core for writing and also as a shield, and ispreferably composed of an NiFe alloy, the same as in the conventionalmagnetic head. The upper core layer 29 is preferably composed of amagnetic material having high saturation flux density (Hi-Bs) and/orhigh resistivity (Hi-ρ), such as an Fe₅₀Ni₅₀ alloy or FeCoNi alloy inorder to improve the function as a core for recording.

In the inductive magnetic head, when a recording current is applied tothe coil layer 27, a recording magnetic field is induced in the uppercore layer 29, the lower shielding layer 21, and the lower core layer24, and a magnetic signal is recorded onto a recording medium such as ahard disk by means of a leakage magnetic field from the magnetic gapbetween the tip 29 a of the upper core layer 29 and the lower core layer24.

Although the coil layer 27 shown in FIG. 1 has a single-layeredstructure, a double-layered structure may be acceptable.

FIG. 2 is a longitudinal sectional view of a thin film magnetic head asa second embodiment of the present invention.

In FIG. 2, a lower shielding layer 30 is formed at a predeterminedlength L1 from the surface facing a recording medium (ABS) in the depthdirection (in the right direction in the drawing), and a first magneticmaterial layer 31 is formed in the rear of the lower shielding layer 30with a predetermined distance L2 therebetween. A nonmagnetic materiallayer 32 composed of a nonmagnetic material such as Al₂O₃ is formed inthe distance L2 formed between the lower shielding layer 30 and thefirst magnetic material layer 31. In the present invention, the lowershielding layer 30, the nonmagnetic material layer 32, and the firstmagnetic material layer 31 are formed at the same height t3, and thesurfaces of the individual layers are planarized.

As shown in FIG. 2, the lower core layer 33 extends perpendicularly fromthe first magnetic material layer 31 to over a first gap layer 23 on amagnetoresistive element layer 22.

In this thin film magnetic head, the same as in the thin film magnetichead shown in FIG. 1, a coil layer 27 is also formed in the rear of thelower core layer 33, and in particular, since the lower core layer 33formed on the magnetoresistive element layer 22 is bent perpendicularlytoward the first magnetic material layer 31, a step is formed betweenthe lower core layer 33 and the first gap layer 23. The coil layer 27 isformed at the lower level. Therefore, a second insulating layer 28 onthe coil layer 27 is formed being slightly swelled by t2 from thesurface S of a second gap layer 25 formed on the lower core layer 24, oris formed substantially at the same height as the surface S of thesecond gap layer 25. Thus, the swelling of the second insulating layer28 can be reduced in comparison with the conventional thin film magnetichead.

Accordingly, in the present invention, a resist layer, which is usedwhen an upper core layer 29 is formed, can be formed thinly at asubstantially uniform thickness from on the second gap layer 25 formedon the lower core layer 33 and to on the second insulating layer 28.Therefore, in the present invention, the depth of focus during exposureand development can be decreased and resolution can be improved.Irregular reflection due to differences in focus does not easily occur,and in particular, a narrowly shaped tip 29 a of the upper core layer29, in which the width thereof determines a track width Tw, can beformed properly in a predetermined shape, and thus narrowing of thetrack is enabled.

In the thin film magnetic head shown in FIG. 2, the lower shieldinglayer 30 and the first magnetic material layer 31 can be composed ofdifferent materials, and in particular, the first magnetic materiallayer 31 is preferably composed of a magnetic material having highsaturation flux density and/or high resistivity, such as an Fe₅₀Ni₅₀alloy or FeCoNi alloy.

The reason for this is that when a recording current is applied to thecoil layer 27, a magnetic path is formed over the upper core layer 29,the first magnetic material layer 31, and the lower core layer 33, andthe first magnetic material layer 31 functions only as a core layer ofthe inductive magnetic head.

In contrast, although the lower core layer 33 also functions as a corelayer of the inductive magnetic head, it functions also as an uppershielding layer of the reproducing head, and therefore, the lower corelayer 33 is preferably composed of an NiFe alloy or the like, the sameas in the conventional magnetic head.

In the magnetic head shown in FIG. 2, since the lower shielding layer 30and the first magnetic material layer 31 are formed with a distancetherebetween, the magnetic path formed during writing does not affectthe lower shielding layer 30, and therefore, the magnetic domain of thelower shielding layer 30 is not disturbed, enabling improvement in theshielding function.

In the thin film magnetic head shown in FIG. 2, although the coil layer27 has a single-layered structure, a double-layered structure may beacceptable.

FIG. 3 is a longitudinal sectional view of a thin film magnetic head asa third embodiment of the present invention.

As shown in FIG. 3, in the thin film magnetic head, the same as in thethin film magnetic head shown in FIG. 2, a lower shielding layer 30 isformed at a length L1, and a nonmagnetic material layer 32 composed of anonmagnetic material, such as Al₂O₃, having a length L2 is formed in therear of the lower shielding layer 30. A first magnetic material layer 31is formed in the rear of the nonmagnetic material layer 32. A lower corelayer 33 extends perpendicularly from the first magnetic material layer31 to over a first gap layer 23 on a magnetoresistive element layer 22.

In this embodiment, a coil layer 40 is formed in a double-layeredstructure, and a second insulating layer 41 for covering the coil layer40 is formed being swelled by t4 from the surface S of a second gaplayer 25 on the lower core layer 33. Since the coil layer 40 isdouble-layered, the height t4 of the swelling from the surface S of thegap layer 25 is larger than the height t2 shown in FIG. 1 or 2. However,in the present invention, as shown in FIG. 3, the coil layer 40 isformed in the rear of the lower core layer 33, and the coil layer 40 isformed in a recess formed by the lower core layer 33 and the first gaplayer 23, and therefore, in comparison with the conventional thin filmmagnetic head shown in FIG. 11, the swelling of the second insulatinglayer 41 on the coil layer 40 can be reduced. In particular, a tip 29 aof an upper core layer 29 can be formed in a predetermined narrow shape,thus meeting the demand to narrow the track.

By forming the coil 40 in a double-layered structure, a magnetic pathformed over the core during writing can be shortened, thus enablingimprovement in writing efficiency and reduction in inductance.

In the thin film magnetic head shown in FIG. 3, a second magneticmaterial layer 42 is formed at a base 29 b of the upper core layer 29between the upper core layer 29 and the first magnetic material layer31. When the second magnetic material layer 42 is composed of the samematerial as that of the lower core layer 33, the fabrication process canbe simplified.

However, the second magnetic material layer 42 functions only as a corefor writing, and does not have the shielding function as the lower corelayer 33 does. Therefore, the second magnetic material layer 42 ispreferably composed of a magnetic material having high saturation fluxdensity and/or high resistivity, such as an Fe₅₀Ni₅₀ alloy or FeCoNialloy.

In the thin film magnetic head shown in FIG. 3, when a recording currentis applied to the coil layer 40, a magnetic path is formed over theupper core layer 29, the second magnetic material layer 42, the firstmagnetic material layer 31, and the lower core layer 33.

Next, a method of fabricating a thin film magnetic head in the presentinvention will be described with reference to FIGS. 4 to 10.Hereinafter, a method of fabricating a thin film magnetic head as shownin FIG. 2 or 3, in which a first magnetic material layer 31 is formed inthe rear of a lower shielding layer 30, will be described.

First, as shown in FIG. 4, an underlying layer 50 composed of a magneticmaterial such as an NiFe alloy is formed on a substrate 20. Rectangularresist layers 51 and 52 are formed on the underlying layer 50 byapplying a resist on the underlying layer 50, followed by exposure anddevelopment. There is a distance L1 between the resist layers 51 and 52.

A lower shielding layer 30 composed of an NiFe alloy or the like isformed by plating on the underlying layer 50 at the distance L1 in whichthe resist layers 51 and 52 are not formed. The process, as describedabove, in which the formation of an underlying layer, the formation ofresist layers, exposure and development, and plating are performed, iscalled “frame plating”.

Next, as shown in FIG. 5, by forming resist layers on the lowershielding layer 30 and the underlying layer 50, followed by exposure anddevelopment, a rectangular resist layer 53 is formed on the lowershielding layer 30. A rectangular resist layer 54 is also formed on theunderlying layer 50 separately from the resist layer 53 with apredetermined distance therebetween.

A first magnetic material layer 31 composed of a magnetic material,preferably, having high saturation flux density and/or high resistivity,is formed by plating on the underlying layer 50 between resist layers 53and 54.

As shown in FIG. 5, the resist layer 53 must be formed on the lowershielding layer 30 so as to leave a predetermined distance L2 betweenthe lower shielding layer 30 and the first magnetic material layer 31.As will be described below, a nonmagnetic material layer 32 is formed inthe distance L2.

Next, as shown in FIG. 6, the resist layers 53 and 54 shown in FIG. 5are removed, and the underlying layer 50 formed beneath the resistlayers 53 and 54 is removed by ion milling. That is, the underlyinglayer 50 remains only beneath the lower shielding layer 30 and the firstmagnetic material layer 31.

As shown in FIG. 7, a nonmagnetic material layer 55 composed of Al₂O₃ orthe like is formed on the lower shielding layer 30, the first magneticmaterial layer 31, and the substrate 20, and the surface of thenonmagnetic material layer 55 is ground by CMP, and furthermore, thesurfaces of the lower shielding layer 30 and the first magnetic materiallayer 31 are ground down to the line B—B. By this step, a nonmagneticmaterial layer 32 can be formed between the lower shielding layer 30 andthe first magnetic material layer 31, and also the lower shielding layer30, the first magnetic material layer 31, and the nonmagnetic materiallayer 32 can be formed at the same height t3.

Next, as shown in FIG. 8, a first gap layer 23 is formed on theplanarized lower shielding layer 30, the nonmagnetic material layer 32,and the first magnetic material layer 31, and a magnetoresistive elementlayer 22 is formed on the first gap layer 23 on the lower shieldinglayer 30.

A resist layer (not shown in the drawing) is then formed on themagnetoresistive element layer 22, and the magnetoresistive elementlayer 22 is formed into a predetermined pattern by exposure anddevelopment. In the present invention, since the surfaces of the lowershielding layer 30, the nonmagnetic material layer 32, and the firstmagnetic material layer 31 are planarized, the resist layer for formingthe magnetoresistive element layer 22 into a predetermined shape can beformed at a uniform thickness, and thus a track width Tw of themagnetoresistive element layer 22 can be formed at a predetermined size.

Next, a hole 23 a is made in the first gap layer 23 so as to reach thefirst magnetic material layer 31 in the rear of the magnetoresistiveelement layer 22. The hole 23 a is preferably made perpendicularly.

A lower core layer 33, which extends from the hole 23 a to over thefirst gap layer 23 on the magnetoresistive element layer 22, is formedby frame plating. Thus, the lower core layer 33 can be formed in contactwith the first magnetic material layer 31.

Next, a second gap layer 25 composed of a nonmagnetic material is formedfrom on the lower core layer 33 to on the first gap layer 23 in the rearof the lower core layer 33.

A first insulating layer 26 composed of an organic material is formed onthe first gap layer 23 in the rear of the lower core layer 33 with thesecond gap layer 25 therebetween, and a coil layer 27 is spirally formedon the first insulating layer 26. A second insulating layer 28 is formedon the coil layer 27.

Next, an upper core layer 29 is formed from on the second gap layer 25on the lower core layer 33 to on the second insulating layer 28 on thecoil layer 27 by frame plating. First, as shown in FIG. 8, an underlyinglayer 56 composed of a magnetic material, such as an NiFe alloy, isformed from on the second gap layer 25 on the lower core layer 33 to onthe second insulating layer 28 on the coil layer 27. A resist layer 57is then formed on the underlying layer 56.

In the present invention, the lower core layer 33 is bentperpendicularly to reach the first magnetic material layer 31, and thecoil layer 27 is formed in the rear of the lower core layer 33. As shownin FIG. 8, since the coil layer 27 is formed on the first gap layer 23formed at a lower level than that of the lower core layer 33, theswelling of the second insulating layer 28 formed on the coil layer 27can be reduced to the level which is slightly higher, by t2, than thesurface of the gap layer 25 on the lower core layer 33, and therefore,the resist layer 57, which is formed from on the second gap layer 25 onthe lower core layer 33 to on the second insulating layer 28 on the coillayer 27, can be formed at a substantially uniform thickness. Inparticular, a thickness t5 of the resist layer 57 formed on the secondgap layer 25 on the lower core layer 33 can be set at substantially thesame thickness as that of the resist layer 57 formed on the secondinsulating layer 28.

Next, in FIG. 9, the resist layer 57 is exposed and developed, and theresist layer 57 which corresponds to a pattern 58 of the upper corelayer 29 is removed. FIG. 9 is a plan view.

As shown in FIG. 9, a tip 58 a of the pattern 58 is narrowly shaped, andthe width thereof corresponds to a track width Tw. In the presentinvention, as described above, since the thickness of the resist layer57 can be formed at a substantially uniform value, the pattern 58including the tip 58 a which must be formed with particular precisioncan be properly formed.

Next, the upper core layer 29 is plated within the pattern 58, and theremaining resist layer 57 is removed. By removing the thin film laminateon the left side of the line A—A shown in FIG. 10, a thin film magnetichead in the present invention is completed. A magnetic material used asthe upper core layer 29 preferably has high saturation flux densityand/or high resistivity.

Although the coil layer 27 has a single-layered structure in thefabricating method described above, the coil layer 27 may be formed in adouble-layered structure, the same as the coil layer 40 shown in FIG. 3.

Furthermore, as shown in FIG. 3, the second magnetic material layer 42may be formed between the base 29 b of the upper core layer 29 and thefirst magnetic material layer 31.

When the second magnetic material layer 42 is composed of the samematerial as that of the lower core layer 33, the second magneticmaterial layer 42 is preferably formed by frame plating at the same timethe lower core layer 33 is formed. When the second magnetic materiallayer 42 is composed of a different material from that of the lower corelayer 33, after the lower core layer 33 is formed by frame plating inaccordance with fabricating steps shown in FIGS. 4 to 6, a resist layeris formed on the lower core layer 33 to protect the lower core layer 33and the second magnetic material layer 42 is formed by frame plating.The second gap layer 25 is then formed on the lower core layer 33, thefirst gap layer 23, and the second magnetic material layer 42.

The second magnetic material layer 42 is preferably composed of amagnetic material having high saturation flux density and/or highresistivity.

As described above, in the present invention, a lower core layer isformed from on a magnetoresistive element layer to, by being bentperpendicularly, on a lower shielding layer or a first magnetic materiallayer formed in the rear of the lower shielding layer. A coil layer isformed in the rear of the lower core layer. Thus, the swelling of aninsulating layer formed on the coil layer can be reduced in relation tothe surface of the lower core layer, and a resist layer for forming anupper core layer can be formed thinly at a substantially uniformthickness. Therefore, the upper core layer, in particular, the tipthereof, can be formed at a predetermined shape, thus meeting the demandto narrow the track.

In the present invention, as shown in FIG. 2, the first magneticmaterial layer 31 may be formed in the rear of the lower shielding layer30 with a predetermined distance L2 therebetween. The first magneticmaterial layer 31 is preferably composed of a magnetic material havinghigh saturation flux density and/or high resistivity.

In the present invention, as shown in FIG. 3, the coil layer 40 may havea double-layered structure, and the second magnetic material layer 42may be formed between the base 29 b of the upper core layer 29 and thefirst magnetic material layer 31. In such a case, the second magneticmaterial layer 42 is preferably composed of a magnetic material havinghigh saturation flux density and/or high resistivity.

In the present invention, as described in detail, a lower core layer isformed from on a magnetoresistive element layer to, by being bentperpendicularly, on a lower shielding layer or a first magnetic materiallayer formed in the rear of the lower shielding layer. A coil layer isformed in the rear of the lower core layer. Thus, the swelling of aninsulating layer (second insulating layer) formed on the coil layer canbe reduced in relation to the surface of the lower core layer, and aresist layer for forming an upper core layer can be formed thinly at asubstantially uniform thickness. Therefore, the upper core layer, inparticular, the tip thereof, can be formed, by frame plating, at apredetermined track width, thus meeting the demand to narrow the track.

In the present invention, a coil layer is preferably formed in adouble-layered structure, and even if the coil layer has adouble-layered structure, the swelling of an insulating layer (secondinsulating layer) formed on the coil layer can be greatly reduced incomparison with conventional magnetic heads, and the tip of an uppercore layer can be formed at a predetermined track width, thus meetingthe demand to narrow the track. By forming the coil layer in adouble-layered structure, a magnetic path during writing can beshortened, thus enabling the improvement in writing efficiency and thereduction in inductance.

In the present invention, when a first magnetic material layer is formedin the rear of a lower shielding layer and when a second magneticmaterial layer is formed between the base of an upper core layer and thelower shielding layer or the first magnetic material layer, the firstmagnetic material layer and the second magnetic material layer arepreferably composed of a magnetic material having high saturation fluxdensity and/or high resistivity, the same as the upper core layer.

In the present invention, surfaces of a lower shielding layer and afirst magnetic material layer are planarized, and thus a resist layer,which is used when a magnetoresistive element layer on the lowershielding layer is formed at a predetermined pattern, can be formed at auniform thickness, and the track width of the magnetoresistive elementlayer can be formed at a predetermined width.

In the present invention, since a lower core layer is perpendicularlybent and formed on a lower shielding layer or a first magnetic materiallayer and a coil layer is formed in the rear of the lower core layer,the coil layer can be formed on the planarized lower shielding layer orfirst magnetic material layer, and thus the coil layer can be easilyformed in a predetermined shape.

What is claimed is:
 1. A thin film magnetic head comprising: a lowershielding layer comprising a magnetic material; a first magneticmaterial layer at the rear of the lower shielding layer, the firstmagnetic material layer being magnetically separated from the lowershielding layer by an nonmagnetic material located therebetween; anonmagnetic MR gap layer on the lower shielding layer; amagnetoresistive element layer in the MR gap layer facing a recordingmedium; a lower core layer comprising a magnetic material on the MR gaplayer; an upper core layer comprising a magnetic material opposed to thelower core layer with a nonmagnetic gap layer therebetween at thesurface facing the recording medium; and a coil layer for inducing arecording magnetic field in the lower core layer and the upper corelayer, said coil layer comprising a wound coil surrounded by insulatinglayers, wherein the lower core layer extends from the position facingthe recording medium to the rear of the magnetoresistive element layer,bends toward the first magnetic material layer in the rear, and comesinto magnetic contact with the first magnetic material layer; the coillayer lies in the rear of a step of the back end of the lower core layerand lies magnetically between the first magnetic material layer and theupper core layer; and a magnetic path induced by the coil layer passesthrough the first magnetic material layer, the lower core layer, and theupper core layer.
 2. A thin film magnetic head according to claim 1,wherein a nonmagnetic material layer is provided between the lowershielding layer and the first magnetic material layer, and the lowershielding layer, the first magnetic material layer, and the nonmagneticmaterial layer have the same thickness.
 3. A thin film magnetic headaccording to claim 2, wherein the lower shielding layer and the firstmagnetic material layer comprise different magnetic materials.
 4. A thinfilm magnetic head according to claim 3, wherein the first magneticmaterial layer comprises a magnetic material having higher saturationflux density than that of the lower shielding layer.
 5. A thin filmmagnetic head according to claim 4, wherein the first magnetic materiallayer comprises a magnetic material having higher resistivity than thatof the lower shielding layer.
 6. A thin film magnetic head according toclaim 3, wherein the first magnetic material layer comprises a magneticmaterial having higher resistivity than that of the lower shieldinglayer.
 7. A thin film magnetic head according to claim 1, wherein thelower shielding layer and the first magnetic material layer comprisedifferent magnetic materials.
 8. A thin film magnetic head according toclaim 7, wherein the first magnetic material layer comprises a magneticmaterial having higher saturation flux density than that of the lowershielding layer.
 9. A thin film magnetic head according to claim 8,wherein the first magnetic material layer comprises a magnetic materialhaving higher resistivity than that of the lower shielding layer.
 10. Athin film magnetic head according to claim 7, wherein the first magneticmaterial layer comprises a magnetic material having higher resistivitythan that of the lower shielding layer.
 11. A thin film magnetic headaccording to claim 1, wherein a second magnetic material layer is formedon the first magnetic material layer in the rear of the coil layer, andthe upper core layer is brought into contact with the second magneticmaterial layer.
 12. A thin film magnetic head according to claim 11,wherein the second magnetic material layer comprises a magnetic materialhaving high saturation flux density.
 13. A thin film magnetic headaccording to claim 12, wherein the second magnetic material layercomprises a magnetic material having high resistivity.
 14. A thin filmmagnetic head according to claim 13, wherein the coil layer is formed ina double-layered structure, and at least the lower coil layer is at therear of a step of the back end of the lower core layer.
 15. A thin filmmagnetic head according to claim 11, wherein the second magneticmaterial layer comprises a magnetic material having high resistivity.16. A thin film magnetic head according to claim 15, wherein the coillayer is formed in a double-layered structure, and at least the lowercoil layer is at the rear of a step of the back end of the lower corelayer.
 17. A thin film magnetic head according to claim 2, wherein thecoil layer is formed in a double-layered structure, and at least thelower coil layer is placed in the rear of a step of the back end of thelower core layer.